1. Field of Invention
This invention relates to a wristwatch with the function of measuring and processing a three-lead electrocardiogram (ECG) and more particularly, to a wrist-watch that is capable of measuring a three-lead ECG and providing event-related reminders for alerting users to measure an ECG in a critical moment determined by a sensing system or by the user. In addition, this invention is related to a method for measuring the three-lead ECG by the wristwatch.
2. Description of Related Art
Regularly tracking on changes in cardiac function is usually suggested for the elderly to maintain fitness. In a hospital, a three-lead ECG measurement has been widely used to monitor cardiac function. While accepting a cardiac assessment in the hospital, it can often cost time, can increase the risk to get an infection and may not be convenient for the elderly. To be capable of measuring an ECG conveniently, portable ECG recording devices have been developed.
Although portable ECG measuring devices have been introduced to record an ECG outside a hospital, the need to wear electrodes on the chest and carry cables connecting to the device makes it difficult to use on an ambulatory and daily base. Some wristwatches have been made for measuring heart rates or heart pulses but have not been equipped with a three-lead ECG measurement and arrhythmia analysis which provides more detail information about the cardiac system.
A standard three-lead ECG indicates a measurement of cardiac potentials leaving from the heart in 3 directions, toward the right-arm (RA), toward the left-arm (LA), and toward the left leg (LL). The lead I of the ECG is the cardiac potential difference between LA and RA (LA−RA), the lead II of the ECG is the cardiac potential difference between LL and RA (LL−RA), and the lead III of the ECG is the cardiac potential difference between LL and LA (LL−LA). Also, 3 augmented leads (lead AVR, AVL and AVF) can be calculated based on the standard three-lead ECG. Lead AVR is RA−(LA+LL)/2=−(I+II)/2, lead AVL is LA−(RA+LL)/2=(I−III)/2, and lead AVF is LL−(RA+LA)/2=(II+III)/2.
To meet the need of convenience and medical expertise, it is desirable to have a portable device, e.g. a wristwatch, which can measure and process a three-lead ECG without extra cable connections. Further, the three-lead ECG data acquired by a portable device, which can be recorded and transmitted to a personal and hospital computer, will be highly convenient and needed.